
Your OH needs to stop trying. With a nervous dog, the worst thing you can do is TRY to be friends, because it's putting pressure on the dog. Don't call her, don't expect anything of her, not even to take food out of a hand, even that can be too much. he needs to ignore her to prove he is no threat. It has to be entirely on the dog's terms initially, she has to come to your OH out of her own free will without any strings attached -and even a treat in a hand IS strings attached. So start very slowly (and expect a slow process -weeks if not months) with your OH not looking at the dog and just dropping treats on the floor -at first throwing them in her general direction without looking at her, then dropping them at his side etc. I honestly wouldn't have him walk her yet as that won't be a nice experience for her and could result in walks being avoided by her full stop.
Edited to say: the process really has to be super slow, once she has got to the stage of taking treats next to his feet on the floor then try treat from hand but DON'T get him to try to stroke her until she is 100 % comfortable with taking treats out of his hand, otherwise she will instantly take a big step back and think it was all just a trick to get to her.